The Brazilian Football Confederation is to send Fifa a dossier resuscitating one of the great controversies in World Cup history - that one of Brazil's top players was allegedly drugged by Argentina when the teams played each other during Italia 90.

Allegations that the left-back Branco drank from a water bottle which the Argentinians had spiked with a tranquilliser were given new weight this week when Argentina's then coach, Carlos Bilardo, appeared to imply that they were true.

Asked about the incident in the magazine Veintitres, Bilardo - who enjoyed a reputation for ruthlessness and guile - said: "I'm not saying it didn't happen." It was not quite an admission of guilt. Yet it was more than enough for the Brazilians, who interpreted the Argentinian's failure to deny categorically the allegations as confirmation of what they had always suspected.

Marco Antonio Teixeira, secretary general of the Brazilian Football Confederation (CBF), said: "This is an extremely serious matter. Next week we will send a dossier to Fifa that has all the reports of the fact and ask for them to take preventative measures if anything is confirmed." Fifa refused to comment on the allegations yesterday.

The incident has long been considered one of the more colourful episodes in the intense rivalry between the South American nations. It ranks alongside the accusation that Argentina bought their 6-0 victory against Peru in the 1978 World Cup, which took them to the final instead of Brazil on goal difference.

In 1990, Brazil and Argentina met in the first round of the knockout stage. Brazil were dominating the match, played in intense heat in Turin, until an Argentinian went down injured. During this interruption Branco - later to play in England with Middlesbrough - drank from a bottle supplied by Argentina's physio Miguel di Lorenzo.

Shortly afterwards, against the run of play, Claudio Caniggia scored the only goal of the game from a Diego Maradona pass, putting Argentina into the quarter-finals. Argentina went on to the final, where they lost to Germany.

Suspicion of foul play was first raised two days later by Branco, who said he had felt dizzy and ill after drinking the water.

Maradona surprisingly reopened interest in the incident when he spoke about it for the first time in a TV interview broadcast last month, joking that he had encouraged the Brazilians to drink from the water bottle. "Afterwards, Branco took the free-kicks and fell over," he said. Following up Maradona's comments, Veintitres asked Bilardo whose idea it was. "I don't know. I'm not saying it didn't happen." The journalist reported that Bilardo contorted his mouth so that he did not smile, as if he were hiding something.

The interview has sparked a war of words between many of the veterans of the 1990 match, which has been given ample space in the sports media of both countries. The angriest comments have come from Brazil's then coach Sebastiao Lazaroni, whose international career ended with the defeat: "This isn't just gamesmanship, it's playing dirty. It doesn't matter if it happened 14 years ago or 14 days; Fifa should punish Bilardo and the physio to make an example of them. Who can guarantee that they didn't behave like this in other games too?"

Even cooller-headed figures have been sucked into the controversy. Brazil's current coach Carlos Alberto Parreira said: "This has got to be better looked into. I know Bilardo and wouldn't have thought that it could happen. If it is true, he was unethical."

In Argentina, Bilardo has accused the press of making up the story and repeated that he knew nothing of any plot to dope the Brazilians. Di Lorenzo insisted that the allegations were all lies.

This drew a fierce reaction from the former Brazil striker Bebeto: "If he denied it, he's being sly." He added that he had been at a dinner where Di Lorenzo admitted everything: "He said that he left the bottles already prepared, and by the way he said he probably didn't do it just with us."

An unexpected voice of moderation came from the CBF president, Ricardo Teixeira, who said that he would not be asking for Fifa to annul the result of the game whatever was discovered.

"They were better than us on the pitch," he said. "Maradona had a great game and Caniggia scored a beautiful goal."

Conspiracy theories

1970 World Cup, Mexico

Gordon Banks drank a bottle of dodgy beer, Peter Bonetti, had a nightmare - England were out of the World Cup, losing to West Germany 3-2 after extra-time.

1978 World Cup, Argentina

The hosts needed to win by three clear goals against Peru and won 6-0, ousting Brazil. Accusations of bribery and corruption.

1995 Rugby World Cup

Sinister Suzie, the phantom waitress was rumoured to be behind the stomach bug that swept through at least half the All Blacks in the week leading up to the final. Some players claimed they had been poisoned. But it was alleged the players had eaten an unauthorised seafood meal on the Friday night before the Ellis Park final, won by South Africa 15-12 after extra-time.